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03-13-2014, 09:14 PM
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Join Date: Apr 2007
Location: Cedar Hill, Tx.
Posts: 159
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Corrosion in Aileron Push Pull tube
Both of my aileron push pull tubes have corrosion on them. One is worse than the other. I seem to remember that 10 % of the thickness is the limit before it has to be replaced. Is that correct?
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member 1 of 6
Metal Feathers Club
RV 7 N706CB
1st flight Oct 18, 08
S/N 72847 tip 200HP CS glass IFR
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03-13-2014, 10:37 PM
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Join Date: Mar 2008
Location: Ramona, CA
Posts: 2,370
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Did you prime them? This tubing isn't alclad, so it needs protection from corrosion.
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03-14-2014, 03:59 AM
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Join Date: Aug 2005
Location: Dallas/Ft Worth, TX
Posts: 5,686
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Quote:
Originally Posted by hudgin
Both of my aileron push pull tubes have corrosion on them. One is worse than the other. I seem to remember that 10 % of the thickness is the limit before it has to be replaced. Is that correct?
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10% is the generally accepted standard, but Van's doesn't actually spec that number in their manual anywhere so if you want an "official" answer you will need to ask Van's.
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Walt Aronow, DFW, TX (52F)
EXP Aircraft Services LLC
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03-14-2014, 05:05 AM
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Join Date: Apr 2007
Location: Cedar Hill, Tx.
Posts: 159
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They were primed with a good coat of zinc chromate. Where they havent corroded the chromate is changing color.
10% is good enough for me, I will change them out. Thanks
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member 1 of 6
Metal Feathers Club
RV 7 N706CB
1st flight Oct 18, 08
S/N 72847 tip 200HP CS glass IFR
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03-14-2014, 07:16 AM
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Join Date: Jan 2005
Location: Twin Cities, MN
Posts: 1,565
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Quote:
Originally Posted by hudgin
Both of my aileron push pull tubes have corrosion on them. One is worse than the other. I seem to remember that 10 % of the thickness is the limit before it has to be replaced. Is that correct?
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Is this from the stick to the bell crank or from the bell crank to the aileron?
I'm wondering because one is a bit easier to inspect on a regular basis than the other...
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Brad Benson, Maplewood MN.
RV-6A N164BL, Flying since Nov 2012!
If you're not making mistakes, you're probably not making anything
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03-15-2014, 06:12 AM
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Join Date: Apr 2007
Location: Cedar Hill, Tx.
Posts: 159
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They corroded under the aileron boot at the net entrance into the fuselage.
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member 1 of 6
Metal Feathers Club
RV 7 N706CB
1st flight Oct 18, 08
S/N 72847 tip 200HP CS glass IFR
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03-15-2014, 08:55 AM
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Join Date: Jan 2007
Location: Battleground
Posts: 4,348
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Quote:
Originally Posted by hudgin
They corroded under the aileron boot at the net entrance into the fuselage.
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Zinc Chromate is a sacrificial coating offering very little abrasion resistance. It makes sense that the boots wore through the coating defeating its ability to protect the base metal. All that was needed was moisture which probably soaked the boot allowing the moisture to sit for periods of time instead of evaporating.
The color change you are seeing in the chromate layer is it is corroding as it is supposed to. However, once it has converted, it no longer can inhibit and the corrosion will seek its next victim.
I would be curious to know what your boot was?
Regardless, a two part epoxy would protect this area better next time.
Good catch.
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Last edited by JonJay : 03-15-2014 at 08:57 AM.
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03-15-2014, 10:02 AM
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Join Date: Apr 2007
Location: Cedar Hill, Tx.
Posts: 159
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The boot material is Naugahyde, is suppose flying in weather IFR captured moisture. The damage has occurred in only a one year time since last annual which is really fast I thought till I learned the tubes are not alclad. The new ones will get epoxy. They say if you learn something new you get to go home but then I'll never get to fly.
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member 1 of 6
Metal Feathers Club
RV 7 N706CB
1st flight Oct 18, 08
S/N 72847 tip 200HP CS glass IFR
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